To determine the concentration of iron II ions in a sample of tap water using colorimetry, follow these steps:1. Prepare a series of standard iron II solutions with known concentrations e.g., 0.1, 0.5, 1, 2, 5, and 10 ppm . You can prepare these by diluting a stock solution of iron II ions.2. Add a colorimetric reagent to each standard solution and the tap water sample. A common reagent for iron II ions is 1,10-phenanthroline, which forms a red-orange complex with iron II ions.3. Allow the solutions to react for a sufficient amount of time e.g., 10-15 minutes for the color to develop fully.4. Measure the absorbance of each standard solution and the tap water sample using a colorimeter or spectrophotometer. The absorbance should be measured at the wavelength of maximum absorbance for the iron II -1,10-phenanthroline complex, which is around 510 nm.5. Plot the absorbance values of the standard solutions against their respective concentrations to create a calibration curve. The calibration curve should be a straight line if the Beer-Lambert law is followed.6. Determine the concentration of iron II ions in the tap water sample by comparing its absorbance value to the calibration curve. Locate the absorbance value of the sample on the y-axis of the calibration curve, and find the corresponding concentration on the x-axis.7. The concentration of iron II ions in the tap water sample is the value obtained from the calibration curve.Keep in mind that this is a simplified explanation of the process, and actual laboratory procedures may require additional steps, controls, and precautions.